The nerves that arise from the lumbar plexus course on the anterior surface of the muscles of the posterior abdominal wall. To identify these nerves, remove the deep investing fascia from these muscles.

Identify the terminal branches of the lumbar plexus. They are the:

iliohypogastric nerve (L1) and ilioinguinal nerve (L1) These nerves are located inferior to the subcostal nerve. They emerge from the lateral border of the psoas major muscle and pass inferiorly and laterally across the quadratus lumborum muscle.